Improved error checking in cross_lattice subroutine.
Improved error checking in cross_lattice subroutine.

smharper/openmc,mit-crpg/openmc,samuelshaner/openmc,wbinventor/openmc,liangjg/openmc,kellyrowland/openmc,shikhar413/openmc,mit-crpg/openmc,mit-crpg/openmc,bhermanmit/openmc,bhermanmit/cdash,shikhar413/openmc,lilulu/openmc,nhorelik/openmc,walshjon/openmc,shenqicang/openmc,sxds/opemmc,johnnyliu27/openmc,samuelshaner/openmc,amandalund/openmc,walshjon/openmc,nhorelik/openmc,sxds/opemmc,johnnyliu27/openmc,shenqicang/openmc,wbinventor/openmc,mjlong/openmc,samuelshaner/openmc,wbinventor/openmc,paulromano/openmc,smharper/openmc,smharper/openmc,keadyk/openmc_mg_prepush,shikhar413/openmc,kellyrowland/openmc,liangjg/openmc,johnnyliu27/openmc,liangjg/openmc,amandalund/openmc,amandalund/openmc,mjlong/openmc,lilulu/openmc,liangjg/openmc,amandalund/openmc,paulromano/openmc,bhermanmit/openmc,paulromano/openmc,keadyk/openmc_mg_prepush,johnnyliu27/openmc,lilulu/openmc,wbinventor/openmc,shikhar413/openmc,paulromano/openmc,walshjon/openmc,walshjon/openmc,keadyk/openmc_mg_prepush,samuelshaner/openmc,mit-crpg/openmc,smharper/openmc